Various industries require sterilized water based fluids in the production of products. For example, various pharmaceuticals are dissolved in sterile water, many beverages require sterile water, and people are desirous of bacteria and virus free drinking water. Specifically, with regard to the beverage industry, there are various spring water based beverages including water and water soluble substances (i.e. minerals) which must be purified of microbes and various hydrocarbons. The U.S. Pat. No. 4,857,081 to applicant and assigned to the assignee of the present invention, issued Aug. 15, 1989, provides a process for separating hydrocarbons and halogenated hydrocarbons from water contaminated therewith. The process utilizes hollow fibers made from regenerated cuproammonium or viscose cellulose. The hollow fibers are tubular nonporous membranes. The process provides a means for drying hydrocarbons and halogenated hydrocarbons, as well as providing a water permeate free of hydrocarbons and halogenated hydrocarbons.
The U.S. patent application Ser. No. 348,893 to applicant and assigned to the assignee of the present invention, filed May 8, 1989, provides a portable device for in situ purification of suspect water wherein microbial agents such as viruses, bacteria, molds, algae and other micro-organisms such as parasites may be effectively removed from available water supplies. The invention provides evidence of the removal of various hydrocarbons from water, as well as the removal of algae from water. The application hypothesizes the use of the invention for the removal of microbes, but there is no evidence presented supporting the ability of the hollow fiber membranes utilized in the system for the removal of minute particulates, such as viruses. The invention disclosed and claimed therein is characterized by the plunger assembly used for pumping the water from a reservoir and through the hollow fiber separating membranes thereof.
The U.S. Pat. No. 4,547,289 to Okano et al, issued Oct. 15, 1985, relates to a filtration apparatus for removing undesirable components from a solution to be treated. The apparatus includes hollow fiber made from membranes such as polysulfones, polyacrylonitriles, various celluloses such cellulose acetate, polyamides, polycarbonates and polyvinylalcohols, although the polysulfones are stated to be the preferred membrane for use. All of the aforementioned membranes, including the specific cellulose acetate example, are porous membranes. These devices provide separation by filtration of substances dependent upon their size and being able to be sieved through the pores of the membrane. Further, when the bundle of hollow fibers comprising the system has deteriorated or has become blocked in the manufacture of purified water, a new bundle of hollow fibers is used to replace the old bundle.
The present invention provides an improved method of disinfecting water wherein a nonfouling membrane system is used for separating water and water soluble substances from water contaminated with microbes, as small as bacterial and viruses. Further, the subject method separates the water and/or water soluble substances from water insoluble hydrocarbons. In other words, the present invention removes minute particulates as well as hydrocarbons from water and water soluble substances. This cannot be achieved by size dependent filtration systems such as that disclosed in the Okano et al patent because many of the minute viruses as well as certain hydrocarbons are of sizes capable of passing through the ultrafiltration type membranes. The present invention, by not using a sieve but rather by utilizing a membrane which imbibes water from a water and/or water soluble substances from a water mixture effectively prevents the passage of microbes and water and soluble hydrocarbons through the membrane thereby providing truly disinfected water.